基于自适应惩罚函数的云工作流调度协同进化遗传算法

云计算为大规模科学工作流应用的执行提供了更高效的运行环境。为了解决云环境中科学工作流调度的代价优化问题,提出了一种基于协同进化的工作流调度遗传算法CGAA。该算法将自适应惩罚函数引入严格约束的遗传算法中,通过协同进化的方法,自适应地调整种群个体的交叉与变异概率,以加速算法收敛并防止种群早熟。通过4种科学工作流的仿真实验结果表明,CGAA算法得到的调度方案在满足工作流调度截止时间约束与降低任务执行代价的综合性能方面优于同类型算法。     

基于局部关键路径与截止期限分配的云工作流调度算法

为了解决云计算中截止期限约束下的工作流调度代价优化问题,提出一种基于局部关键路径和截止期限分配的工作流任务调度算法。为了满足期限约束,并最小化执行代价,算法将工作流任务的调度过程划分为两个阶段:期限分配阶段和调度资源选择阶段。期限分配阶段定义工作流的局部关键路径,并以递归的方式在局部关键路径上的任务间进行子期限分配;调度资源选择阶段在满足任务子期限的同时,为每个任务选择执行代价最低的资源进行任务调度,以实现调度代价优化。分析算法的时间复杂度,并通过一个算例对算法的实现思路进行了详细阐述。通过科学工作流结构的仿真实验,证明了算法不仅可以满足截止期限约束,而且可以降低工作流任务的执行代价。     

云计算环境下虚拟资源自适应调度策略

由于云计算环境下的资源调度与以往网格调度存在巨大差异,提出了一种适应云计算环境的虚拟资源调度方法;首先定义了虚拟资源调度数学模型,然后给出了一种改进的遗传算法,该算法采用经典网格任务调度算法Min-min获取初始最优解,通过海明距离约束产生初始种群,并将调度模型对应的目标函数改进为适应度函数,对交叉算子、变异算子、交叉概率和变异概率等都进行了改进;最后,通过实验证明文中方法能获得全局最早完成时间,与其它方法相比,文中方法所求解的最早完成时间提高了近20%,是一种适合云计算环境的虚拟资源调度方法。     

云环境中基于混合多目标粒子群的科学工作流调度算法

为了更高效地实现科学工作流任务的调度,研究了云环境中的工作流调度多目标优化问题,提出了一种基于非占优排序的混合多目标粒子群优化的工作流调度算法HPSO。首先,建立了截止时间与预算约束下工作流调度的多目标优化模型,模型引入三目标最优化,包括工作流执行跨度、执行代价及执行能耗;其次,设计了一种混合粒子群算法对相互冲突的三目标最优化进行求解,算法通过非占优排序的形式可以得到满足Pareto最优的工作流调度解集合;最后,通过3种科学工作流案例的仿真实验,与同类多目标调度算法NSGA-II,MOPSO和ε-Fuzzy进行了性能比较。实验结果表明,HPSO得到的调度解不仅收敛性更好,而且调度解的空间分布更加一致,更符合云环境中的工作流调度优化。     

基于协同自适应禁忌的多时窗VRP算法实现

针对多时窗VRP,提出了一种对其进行求解的协同禁忌优化算法。首先定义了多时窗VRP的数学模型,通过C-W算法求初始解,采用四种算子进行邻域搜索,定义目标函数衡量候选解好坏;设计了自适应地修改禁忌长度的方法和多个子禁忌算法进行协同寻优的算法;将协同寻优获得的最好最优解作为主禁忌算法初始解进行全局寻优。仿真实验证明,该方法能有效地解决多时间窗的VRP,且与其他方法相比,以较少的迭代次数获得了全局最优解为386.38,具有较大的优越性。     

基于QoS和效用的云计算资源调度模型

针对已有的云计算环境下资源调度模型往往仅考虑任务执行跨度而忽略了能提高用户满意度的效用因素,为此,提出了一种基于用户需求QoS和最大化效用为目标的云计算资源调度模型;首先给出了云计算资源调度的框架和数学模型,并将满足用户预算和最迟完完工时间约束的总效用函数作为优化目标;然后对所有任务构造决策矩阵和归一化处理,并采用拉格朗日松弛求取属性权重向量,从而构造出最终的基于多维属性的总效用函数;最后,定义了基于QoS和以最大化效用为目标的云计算资源调度算法;采用CloudSim工具进行仿真实验,结果表明:文中方法能获得最优的资源调度方案,且与其它方法相比,具有较少的平均执行时间和执行花费,具有较大的优越性。     

云环境下基于预算分配的科学工作流调度研究

云环境下的科学工作流部署不同于传统的独立任务调度,需同步考虑调度代价与时间问题。为此,提出基于预算分配的科学工作流调度方法,将工作流任务与虚拟机资源间的映射求解分为预算分配和资源提供与调度2个阶段。为优化预算使用,设计基于快优先的预算分配算法(FFTD)和基于慢优先的预算分配算法,实现预算在各任务间的子分配。基于任务最早完成时间的降序排列进行任务选择,在虚拟机可重用的情况下根据单个任务的子预算进行资源分配,保证工作流任务的顺利调度。引入5种常规类型的科学工作流进行实验,测试算法在不同类型工作流结构和不同预算约束下的性能,结果表明,FFTD算法在72%、88%、84%的实验场景中相比BDT-AI算法具有更高的虚拟机资源利用率、预算约束满足率以及更短的调度时间,综合性能更优。     

基于SLA和双向拍卖机制的云计算服务资源分配

针对云计算环境下现有的服务资源分配方法在采用SLA约束时未能考虑到市场因素的问题,设计了一种基于SLA约束并采用双向拍卖机制来实现服务提供商利润最大化的服务资源分配方法;首先,定义了云计算环境下基于SLA的双向拍卖服务资源分配模型,然后设计了服务提供商与用户签约的SLA并实现了到其资源提供商的映射,为了保证资源提供商提供真实可靠的信息,设计了分配函数和支付函数对其进行激励约束;最后,定义了采用SLA和双向拍卖机制对云计算资源进行分配的具体算法;仿真实验表明,文中方法的任务执行成功率最高,平均约为78.2%,在具有较少的SLA违约率的同时服务提供商能获取较多的利润,同时较其它方法具有较高的任务成功率,具有很强的可行性。     

军事网格工作流调度算法研究

针对军事网格应用及工作流的特点,提出一种基于网格工作流分割的调度算法。采用基于有向无环图的工作流建模方法,对网格工作流的相关概念进行形式化定义。在确定基本工作流之间的复合关系后,对网格工作流中的任务实施调度。实例结果表明,该算法能减少网格工作流的任务执行时间,具有较好的调度性能。     

基于多约束图分割机制的科学工作流调度

为了解决数据密集型环境下的科学工作流应用调度问题,提出一种基于多约束图分割的工作流调度算法。解决标准图分割方法中顶点维度单一而无法反映任务并行性的问题;设计多维度的顶点权重矢量机制,通过有向边的修剪,在所有维度上实现权重和的均衡;得到最小化的任务间数据传输量,降低通信代价。以Montage工作流结构为例进行仿真实验,结果表明,该算法仅以较小的图分割时间代价使得工作流调度过程中的访问量降低了14%,调度时间降低了31%。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.